diff options
| -rw-r--r-- | drivers/tty/sysrq.c | 276 |
1 files changed, 202 insertions, 74 deletions
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 16ee6cee07d..77fcad4371c 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -41,6 +41,7 @@ #include <linux/slab.h> #include <linux/input.h> #include <linux/uaccess.h> +#include <linux/moduleparam.h> #include <asm/ptrace.h> #include <asm/irq_regs.h> @@ -576,8 +577,71 @@ struct sysrq_state { bool active; bool need_reinject; bool reinjecting; + + /* reset sequence handling */ + bool reset_canceled; + unsigned long reset_keybit[BITS_TO_LONGS(KEY_CNT)]; + int reset_seq_len; + int reset_seq_cnt; + int reset_seq_version; }; +#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */ +static unsigned short sysrq_reset_seq[SYSRQ_KEY_RESET_MAX]; +static unsigned int sysrq_reset_seq_len; +static unsigned int sysrq_reset_seq_version = 1; + +static void sysrq_parse_reset_sequence(struct sysrq_state *state) +{ + int i; + unsigned short key; + + state->reset_seq_cnt = 0; + + for (i = 0; i < sysrq_reset_seq_len; i++) { + key = sysrq_reset_seq[i]; + + if (key == KEY_RESERVED || key > KEY_MAX) + break; + + __set_bit(key, state->reset_keybit); + state->reset_seq_len++; + + if (test_bit(key, state->key_down)) + state->reset_seq_cnt++; + } + + /* Disable reset until old keys are not released */ + state->reset_canceled = state->reset_seq_cnt != 0; + + state->reset_seq_version = sysrq_reset_seq_version; +} + +static bool sysrq_detect_reset_sequence(struct sysrq_state *state, + unsigned int code, int value) +{ + if (!test_bit(code, state->reset_keybit)) { + /* + * Pressing any key _not_ in reset sequence cancels + * the reset sequence. + */ + if (value && state->reset_seq_cnt) + state->reset_canceled = true; + } else if (value == 0) { + /* key release */ + if (--state->reset_seq_cnt == 0) + state->reset_canceled = false; + } else if (value == 1) { + /* key press, not autorepeat */ + if (++state->reset_seq_cnt == state->reset_seq_len && + !state->reset_canceled) { + return true; + } + } + + return false; +} + static void sysrq_reinject_alt_sysrq(struct work_struct *work) { struct sysrq_state *sysrq = @@ -604,100 +668,121 @@ static void sysrq_reinject_alt_sysrq(struct work_struct *work) } } -static bool sysrq_filter(struct input_handle *handle, - unsigned int type, unsigned int code, int value) +static bool sysrq_handle_keypress(struct sysrq_state *sysrq, + unsigned int code, int value) { - struct sysrq_state *sysrq = handle->private; bool was_active = sysrq->active; bool suppress; - /* - * Do not filter anything if we are in the process of re-injecting - * Alt+SysRq combination. - */ - if (sysrq->reinjecting) - return false; + switch (code) { - switch (type) { + case KEY_LEFTALT: + case KEY_RIGHTALT: + if (!value) { + /* One of ALTs is being released */ + if (sysrq->active && code == sysrq->alt_use) + sysrq->active = false; - case EV_SYN: - suppress = false; + sysrq->alt = KEY_RESERVED; + + } else if (value != 2) { + sysrq->alt = code; + sysrq->need_reinject = false; + } break; - case EV_KEY: - switch (code) { + case KEY_SYSRQ: + if (value == 1 && sysrq->alt != KEY_RESERVED) { + sysrq->active = true; + sysrq->alt_use = sysrq->alt; + /* + * If nothing else will be pressed we'll need + * to re-inject Alt-SysRq keysroke. + */ + sysrq->need_reinject = true; + } - case KEY_LEFTALT: - case KEY_RIGHTALT: - if (!value) { - /* One of ALTs is being released */ - if (sysrq->active && code == sysrq->alt_use) - sysrq->active = false; + /* + * Pretend that sysrq was never pressed at all. This + * is needed to properly handle KGDB which will try + * to release all keys after exiting debugger. If we + * do not clear key bit it KGDB will end up sending + * release events for Alt and SysRq, potentially + * triggering print screen function. + */ + if (sysrq->active) + clear_bit(KEY_SYSRQ, sysrq->handle.dev->key); - sysrq->alt = KEY_RESERVED; + break; - } else if (value != 2) { - sysrq->alt = code; - sysrq->need_reinject = false; - } - break; + default: + if (sysrq->active && value && value != 2) { + sysrq->need_reinject = false; + __handle_sysrq(sysrq_xlate[code], true); + } + break; + } - case KEY_SYSRQ: - if (value == 1 && sysrq->alt != KEY_RESERVED) { - sysrq->active = true; - sysrq->alt_use = sysrq->alt; - /* - * If nothing else will be pressed we'll need - * to re-inject Alt-SysRq keysroke. - */ - sysrq->need_reinject = true; - } + suppress = sysrq->active; - /* - * Pretend that sysrq was never pressed at all. This - * is needed to properly handle KGDB which will try - * to release all keys after exiting debugger. If we - * do not clear key bit it KGDB will end up sending - * release events for Alt and SysRq, potentially - * triggering print screen function. - */ - if (sysrq->active) - clear_bit(KEY_SYSRQ, handle->dev->key); + if (!sysrq->active) { - break; + /* + * See if reset sequence has changed since the last time. + */ + if (sysrq->reset_seq_version != sysrq_reset_seq_version) + sysrq_parse_reset_sequence(sysrq); - default: - if (sysrq->active && value && value != 2) { - sysrq->need_reinject = false; - __handle_sysrq(sysrq_xlate[code], true); - } - break; + /* + * If we are not suppressing key presses keep track of + * keyboard state so we can release keys that have been + * pressed before entering SysRq mode. + */ + if (value) + set_bit(code, sysrq->key_down); + else + clear_bit(code, sysrq->key_down); + + if (was_active) + schedule_work(&sysrq->reinject_work); + + if (sysrq_detect_reset_sequence(sysrq, code, value)) { + /* Force emergency reboot */ + __handle_sysrq(sysrq_xlate[KEY_B], false); } - suppress = sysrq->active; + } else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) { + /* + * Pass on release events for keys that was pressed before + * entering SysRq mode. + */ + suppress = false; + } - if (!sysrq->active) { - /* - * If we are not suppressing key presses keep track of - * keyboard state so we can release keys that have been - * pressed before entering SysRq mode. - */ - if (value) - set_bit(code, sysrq->key_down); - else - clear_bit(code, sysrq->key_down); + return suppress; +} - if (was_active) - schedule_work(&sysrq->reinject_work); +static bool sysrq_filter(struct input_handle *handle, + unsigned int type, unsigned int code, int value) +{ + struct sysrq_state *sysrq = handle->private; + bool suppress; - } else if (value == 0 && - test_and_clear_bit(code, sysrq->key_down)) { - /* - * Pass on release events for keys that was pressed before - * entering SysRq mode. - */ - suppress = false; - } + /* + * Do not filter anything if we are in the process of re-injecting + * Alt+SysRq combination. + */ + if (sysrq->reinjecting) + return false; + + switch (type) { + + case EV_SYN: + suppress = false; + break; + + case EV_KEY: + suppress = sysrq_handle_keypress(sysrq, code, value); break; default: @@ -785,7 +870,20 @@ static bool sysrq_handler_registered; static inline void sysrq_register_handler(void) { + extern unsigned short platform_sysrq_reset_seq[] __weak; + unsigned short key; int error; + int i; + + if (platform_sysrq_reset_seq) { + for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) { + key = platform_sysrq_reset_seq[i]; + if (key == KEY_RESERVED || key > KEY_MAX) + break; + + sysrq_reset_seq[sysrq_reset_seq_len++] = key; + } + } error = input_register_handler(&sysrq_handler); if (error) @@ -802,6 +900,36 @@ static inline void sysrq_unregister_handler(void) } } +static int sysrq_reset_seq_param_set(const char *buffer, + const struct kernel_param *kp) +{ + unsigned long val; + int error; + + error = strict_strtoul(buffer, 0, &val); + if (error < 0) + return error; + + if (val > KEY_MAX) + return -EINVAL; + + *((unsigned short *)kp->arg) = val; + sysrq_reset_seq_version++; + + return 0; +} + +static struct kernel_param_ops param_ops_sysrq_reset_seq = { + .get = param_get_ushort, + .set = sysrq_reset_seq_param_set, +}; + +#define param_check_sysrq_reset_seq(name, p) \ + __param_check(name, p, unsigned short) + +module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq, + &sysrq_reset_seq_len, 0644); + #else static inline void sysrq_register_handler(void) |